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TRIHEXYPHENIDYL 2MG TABLETS BP

Active substance(s): TRIHEXYPHENIDYL HYDROCHLORIDE

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SUMMARY OF PRODUCT CHARACTERISTICS

1

NAME OF THE MEDICINAL PRODUCT
Trihexyphenidyl 2mg Tablets BP

2.

QUALITATIVE AND QUANTITATIVE COMPOSITION
Each tablet contains 2 mg of trihexyphenidyl hydrochloride BP.
For excipients, see section 6.1.

3.

PHARMACEUTICAL FORM
Tablet
White, flat bevel edged tablets with a breakline.

4.

CLINICAL PARTICULARS

4.1.

Therapeutic indications
1. Treatment of parkinsonism
2. Prevention and control of drug-induced extrapyramidal symptoms
(excluding tardive dyskinesia)

4.2.

Posology and method of administration
Route of administration: Oral
Dosage
Adults (only)
All forms of parkinsonism
Initial dose:
mg

1 – 2 mg gradually increased by 1 – 2 mg increment to 6 – 10

daily according to the patient’s response. Some patients may require 12 – 15
mg daily or more. The maximum daily dose is 20 mg. Postencephalitic
patients tolerate and require larger doses.
Drug-induced parkinsonism
Usual dose: 5 – 10 mg daily
Some cases may be controlled with 1 mg daily.
Elderly:
dosage.

Patients over 65 years of age may require a reduced

The above dosage should be administered in 3 – 4 divided doses daily before
or with meals.
Antimuscarinic treatment of parkinsonism should never be terminated
suddenly.
When changing from one drug to another, withdraw the one in small amounts
while gradually increasing the dose of the other.
Trihexyphenidyl tablets may be given with other drugs employed for the relief
of parkinsonism e.g. other antimuscarinic drugs, levodopa and amantadine.
Dose reduction may be required.

4.3

Contra-indications
Known hypersensitivity to trihexyphenidyl hydrochloride or any of the ingredients.
Incipient glaucoma may be precipitated.

The following are not absolute contraindications, nevertheless caution must be
observed in patients with hypertension,cardiac, liver or kidney dysfunction,
obstructive disease of the gastrointestinal or genitourinary tracts, glaucoma,
and in males with a prostatic hypertrophy.
4.4

Special warnings and precautions for use
Anticholinergic medications, including trihexyphenidyl, should not be withdrawn
abruptly in patients on long-term therapy, to avoid recurrence of the original
symptoms and possible anticholinergic rebound. Prescribers should be aware that
Trihexyphenidyl hydrochloride is liable to abuse as it may produce euphoric effects
or hallucinogenic properties.
Since atropine-like drugs may cause psychiatric symptoms such as confusion,
delusion and hallucinations, trihexyphenidyl should be used with extreme caution in
elderly patients.
As trihexyphenidyl may provoke or exacerbate tardive dyskinesia, it is not
recommended for use in patients with this condition.

Since trihexyphenidyl has been associated with clinical worsening of myasthenia
gravis, the drug should be avoided or used with great caution in patients with
myasthenia gravis.
Patients with arteriosclerosis or those with a history of idiosyncrasy to other drugs
may be more likely to develop severe mental reactions to trihexyphenidyl.
Since the treatment is to be continued for an indefinite period the patient should be
carefully supervised over the long term.
Avoid sudden discontinuation of treatment.
Patients with rare hereditary problems of galactose intolerance, the LAPP lactase
deficiency, glucose-galactose malabsorption should not take this medicine.

4.5

Interaction with other medicinal products and other forms of interactions
Concurrent use of trihexyphenidyl hydrochloride with drugs possessing antimuscarinic effects such as antihistamines increases the side-effects such as blurred
vision, dry mouth, urine retention and constipation; concomitant use can also lead to
confusion in the elderly. Interactions do not generally apply to antimuscarinics used
by inhalation.
Concurrent use of trihexyphenidyl hydrochloride with nefopam increases
antimuscarinic effects.
Concurrent use of tricyclic anti-depressants and monoamine oxidase inhibitors with
trihexyphenidyl hydrochloride increases the antimuscarinic side-effects and may also
cause excitation, confusion and hallucination.
Concurrent use of trihexyphenidyl hydrochloride with ketoconazole reduces the
absorption of the latter.
Concurrent use of trihexyphenidyl with anti-histamine increases the antimuscarinic
side-effects.
Concurrent use of trihexyphenidyl hydrochloride with disopyramide increases the
antimuscarinic effects.
Concurrent use of trihexyphenidyl hydrochloride with phenothiazines increases the
antimuscarinic effect (but reduces plasma concentrations).
Increased antimuscarinic side-effects are observed with amantadine and absorption of
levodopa is possibly reduced.
Concurrent use of trihexyphenidyl hydrochloride with metoclopramide and
domperidone antagonises gastro-intestinal effects.
Antimuscarinics reduce the effects of sublingual nitrates due to failure to dissolve
under the tongue owing to dry mouth.
Parasympathomimetics antagonise the effects of antimuscarinics.

4.6

Use during pregnancy and lactation
Pregnancy
There is inadequate information regarding the use of trihexyphenidyl in pregnancy.
Animal studies are insufficient with regard to effects on pregnancy, embryonal/foetal
development, parturition and postnatal development. The potential risk for humans is
unknown, As with other medication trihexyphenidyl hydrochloride tablets should
only be used during pregnancy if considered essential by the physician.
Lactation
It is unknown whether trihexyphenidyl is excreted in human breast milk. The
excretion of trihexyphenidyl in milk has not been studied in animals. Infants may be
very sensitive to the effects of antimuscarinic medications. Trihexyphenidyl should
not be used during breastfeeding.

4.7

Effects on ability to drive and use machines
Patients should be warned of the potential hazards of driving or operating machinery
if they experience blurred vision or a reduction in alertness. Trihexyphenidyl
hydrochloride may affect the performance of skilled tasks such as driving and using
machinery.

4.8

Undesirable effects
Minor adverse effects include dry mouth, constipation, blurred vision, dizziness and
gastro-intestinal disturbances and will be experienced by 30 – 50% of all patients
treated. This is more frequent in the elderly but reduces with tolerance. Less
commonly urinary retention, tachycardia, hypersensitivity, nervousness and with high
doses in susceptible patients, mental confusion, excitement or euphoria, agitation,
hallucinations, insomnia, restlessness and very occasionally paranoid delusions have
been reported. There have been reports of abuse of trihexiphenidyl due to its euphoric
and hallucinogenic properties and psychiatric disturbances which may necessitate
discontinuation of treatment; impaired memory (immediate and short-term memory
functions) has also been reported.
Reporting of suspected adverse reactions:
Reporting suspected adverse reactions after authorisation of the medicinal product is
important. It allows continued monitoring of the benefit/risk balance of the medicinal
product. Healthcare professionals are asked to report any suspected adverse reactions
via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard.

4.9

Overdose symptoms, emergency procedures, antidotes
Symptoms of overdose with antimuscarinic agents include flushing and
dryness of the skin, dilated pupils, dry mouth and tongue, tachycardia, rapid

respiration, hyperpyrexia, hypertension, nausea, vomiting. Symptoms of CNS
stimulation include marked restlessness, confusion, excitement, paranoid and
psychotic reactions, incoordination, hallucination and delirium and
occasionally seizures or convulsions. A rash may appear on the face and upper
trunk. In severe intoxication central stimulation may give way to CNS
depression, coma, circulatory and respiratory failure and death.
Treatment entails gastric lavage as there is no specific antidote. General
supportive treatment should be carried out. Cold compresses and forcing of
fluid are mandatory. Atropine antagonists may be useful. An adequate airway
should be maintained. Diazepam may be administered to control excitement
and convulsions but the risk of central nervous system depression should be
considered. Hypoxia and acidosis should be corrected. Antiarrhythmic drugs
are not recommended if dysrhythmias occur.

5

PHARMACOLOGICAL PROPERTIES

5.1

Pharmacodynamic properties
Pharmacotherapeutic group: Anticholinergic agents; tertiary amines
ATC code: N04A A01
Trihexyphenidyl hydrochloride is an antimuscarinic agent with both central
and peripheral actions. The stimulation of the CNS is followed by depression.
It is also an antispasmodic agent exerting a direct inhibitory effect on the
parasympathetic nervous system and also has a relaxing effect on the smooth
muscles and reduces secretions especially the salivary and the bronchial. It
also reduces perspiration. The biliary and pancreatic secretions are little
affected.

5.2.

Pharmacokinetic properties
Trihexyphenidyl hydrochloride is well absorbed from the gastro-intestinal
tract. The onset of action occurs within 1 hour of oral administration.

5.3.

Preclinical safety data
There are no pre-clinical data of relevance to the prescriber that are additional
to that already included in other sections of the SPC.

6.

PHARMACEUTICAL PARTICULARS

6.1.

List of excipients
Magnesium stearate
Maize starch
Pregelatinised maize starch
Lactose

6.2.

Incompatibilities
None.

6.3.

Shelf life
5 years for opaque plastic containers.
2 years for aluminium/opaque PVC blister packs.

6.4.

Special precautions for storage
Store in a cool dry place.
Keep out of the reach of children.

6.5.

Nature and contents of container
Trihexyphenidyl 2mg Tablets BP are packed in the following containers and
closures.
Opaque plastic containers (securitainers) with plastic caps for all pack sizes.
Opaque plastic container composed of either high density polypropylene or
high density polyethylene with a tamper-evident or child resistant tamper
evident closure composed of high density polyethylene for all pack sizes (28,
30, 42, 50, 56, 60, 84, 90, 100, 112, 250, 500 and 1000) and packaging
inclusion of standard polyether foam or polyethylene or polypropylene made
filler.
Blister packs of aluminium/opaque PVC. It is subsequently packed in printed
boxboard cartons in pack sizes of 28, 30, 42, 56, 60, 84, 90 and 112.

Not all pack sizes may be marketed.

6.6.

Instructions for use/handling
No special instructions for use/handling.

7.

MARKETING AUTHORISATION HOLDER
Crescent Pharma Limited.
Units 3 and 4
Quidhampton Business Units
Polhampton Lane
Overton
Hants RG25 3ED, UK

8.

MARKETING AUTHORISATION NUMBER(S)
PL 20416/0029

9.
DATE OF FIRST AUTHORISATION/RENEWAL OF THE
AUTHORISATION
13 February 2004

10

DATE OF REVISION OF THE TEXT
15/07/2015

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Source: Medicines and Healthcare Products Regulatory Agency

Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective or appropriate for any given patient. If you have questions about the substances you are taking, check with your doctor, nurse or pharmacist.

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